Colorectal cancer (CRC) is the third most diagnosed cancer in the United States among both men and women, with approximately 150,000 new cases expected in 2008. It is also the second leading cause of cancer deaths in the U.S. with nearly 50,000 expected to die from CRC this year. As with most cancers, early detection is the key to improved survival rates. The objective of this research is to improve early detection of CRC by developing new optical methods for non-invasively assessing the health status of colorectal tissues. To achieve this goal, we propose to develop complimentary coherence imaging methods for screening and surveillance of colorectal epithelium. The new optical methods are based on the principle of coherence imaging. This key attribute of this imaging approach is that it enables depth resolved measurements with ~10 [unreadable]m resolution up to a depth of on of CRC by developing new optical methods for non-invasively assessing the health status of colorectal tissues. To achieve this goal, we propose to develop complimentary coherence imaging methods for screening and surveillance of colorectal epithelium. The new optical methods are based on the principle of coherence imaging. This key att studies. 2) Animal studies. We will execute experiments with animal tissues to define the capabilities of both coherence imaging methods for assessing the pathology of colorectal epithelial tissues. We have selected the azoxymethane (AOM) induced rat carcinogenesis model, which is commonly used for chemopreventive studies of CRC. 3) Ex vivo human tissue studies. We will undertake studies of ex vivo human tissues to demonstrate that a) a/LCI technology can detect pre-cancerous lesions in colorectal tissues from patients with irritable bowel disease (IBD) and b) our white light OCT method will generates suitable tissue images for co-registration purposes.